1. Field of the Invention
The present invention relates generally to a display device, and more particularly, to a projection type display device such as a liquid crystal projector.
2. Description of the Prior Art
In a liquid crystal projector, an image displayed on a screen may, in some cases, be distorted depending on the positional relationship between a liquid crystal panel and the screen. In such a case, in order to correct the distortion of the displayed image, the displayed image is subjected to trapezoidal distortion correction. When it is desired to adjust the size of the image displayed on the screen, the displayed image is subjected to reduction/enlargement processing depending on the desire of a user.
Image deformation processing such as trapezoidal distortion correction processing or enlargement/reduction processing has been conventionally performed in the following manner. That is, the user enters an image deformation command such as a trapezoidal distortion correction command or an enlargement/reduction command using an UP key or a DOWN key by an input device such as a remote controller or a keyboard. The amount of trapezoidal distortion and the rate of enlargement change depending on a time period during which the key is pushed down.
A CPU sequentially calculates parameters relating to image deformation, that is, the amount of trapezoidal distortion, the rate of enlargement, and so forth depending on the command entered into the input device, and sets, every time the parameter relating to image deformation is calculated, the obtained parameter in a digital circuit such as a gate array. The gate array performs the image deformation processing on the basis of the set parameters.
In this method, the parameters relating to image deformation are managed by the CPU. Accordingly, the parameters finally set in the image deformation processing can be recorded on a nonvolatile memory or the like. Even if the circuit is returned to its initial state by turning the power off or on, therefore, it is possible to reproduce the same image deformed state as before by setting the parameters recorded on the nonvolatile memory in the gate array again.
In a method in which the CPU sequentially calculates the parameters depending on an UP key or DOWN key operation by the user, it takes certain time to calculate the parameters. Accordingly, the parameters are intermittently set in the gate array by the CPU, so that a deforming operation is awkward.
In order to solve this problem, when the command entered into the input device is directly set in the gate array, and the gate array calculates the parameters such as the amount of trapezoidal distortion and the rate of enlargement, a smooth image deforming operation can be performed irrespective of the performance of the CPU.
However, this method makes it impossible to reproduce, when the deformed state is returned to an initial state by turning the power off or on or switching a screen, for example, because the CPU does not manage the parameters, the same deformed state as before.
An object of the present invention is to provide a display device capable of performing a smooth image deforming operation as well as capable of reproducing the same deformed state as before when the deformed state is returned to an initial state by turning the power off or on or switching a screen, for example.
In a display device comprising a digital circuit for subjecting an input image to image deformation processing, an operating unit for entering an image deformation command, a CPU into which the image deformation command from the operating unit is entered, and a nonvolatile memory controlled by the CPU, the CPU continuing to transmit, when the image deformation command from the operating unit continues to be entered, the image deformation command to the digital circuit, the digital circuit sequentially making calculation for image deformation when the image deformation command continues to be transmitted from the CPU, to perform the image deformation processing such that the degree of image deformation is gradually increased, a first display device according to the present invention is characterized in that the CPU comprises means for receiving, when the image deformation processing by the digital circuit is terminated, the degree of image deformation at the time of the termination from the digital circuit, and storing the received degree of image deformation in the nonvolatile memory, and means for causing, when an image deformed state is returned to an initial state before the deformation by turning the power of the display device on or off, for example, the digital circuit to subject the input image to the image deformation processing until the degree of image deformation stored in the nonvolatile memory is reached on the basis of the degree of image deformation stored in the nonvolatile memory.
In a display device comprising a digital circuit for subjecting an input image to image deformation processing, an operating unit for entering an image deformation command, a control circuit into which the image deformation command from the operating unit is entered, and a nonvolatile memory controlled by the control circuit, the control circuit continuing to transmit, when the image deformation command from the operating unit continues to be entered, the image deformation command to the digital circuit, the digital circuit sequentially making calculation for image deformation when the image deformation command continues to be transmitted from the control circuit, to perform the image deformation processing such that the degree of image deformation is gradually increased, a second display device according to the present invention is characterized in that the control circuit comprises a circuit for receiving, when the image deformation processing by the digital circuit is terminated, the degree of image deformation at the time of the termination from the digital circuit, and storing the received degree of image deformation in the nonvolatile memory, and a circuit for causing, when an image deformed state is returned to an initial state before the deformation by turning the power of the display device on or off, for example, the digital circuit to subject the input image to the image deformation processing until the degree of image deformation stored in the nonvolatile memory is reached on the basis of the degree of image deformation stored in the nonvolatile memory.
An example of the digital circuit is one for subjecting the input image to trapezoidal distortion correction processing. In this case, the degree of image deformation is the amount of trapezoidal distortion.
An example of the display device is one for subjecting the input image to image enlargement/reduction processing. The degree of image deformation is the rate of image enlargement at the time of enlarging the image, while being the rate of image reduction at the time of reducing the image.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.